Many solar concentrators comprise a single optical element, such as a single lens, mirror, or reflector. Examples of such concentrators include dish and trough concentrators. Other solar concentrators comprise an array of optical elements that are individually adjustable to track the position of the sun in the sky. One type of arrayed concentrator is the “heliostat array”. In a heliostat array, a field of reflective optical elements concentrates solar energy on a collector having dimensions that are small compared to the dimensions of the array. The orientation of the optical elements in a heliostat array can be individually adjustable, thereby allowing the focal point of the array to remain on the collector over the course of a day and during different seasons. Such an arrangement is often referred to as a “tracking” heliostat array.
In a conventional tracking heliostat array, configuring each optical element to be individually movable typically requires a large amount of expensive motorized equipment. For example, in one conventional configuration, two motors are used to adjust the orientation of each element in the tracking heliostat array. Thus, using this configuration, a tracking heliostat array comprising a 10×10 array of mirrors uses 200 motors to adjust the orientation of the mirrors. In addition to causing the array to be undesirably expensive, this large amount of motorized equipment results in an array that is relatively heavy, which is particularly disadvantageous for applications where weight is a significant factor, such as for rooftop mounted applications.